package 接口;


public class Test {
	public static void main(String[] args) {
		Student.say();
	}
}

abstract class AbstractUser {

}

class Student extends AbstractUser {
	static void say() {
		System.out.println("123");
	}

	void print(AbstractUser abstractUser) {
		Student student = (Student) abstractUser;
		student.say();
	}
}
